Feeling a bit overwhelmed and confused

[Bhp91126]

This is a tough one. If your boyfriend had written about being with this controlling guy, who keeps checking in with him multiple times per day, didn't like him being with other people I would immediately tell him: big red flag, run for the hills.

But for the red flag himself advice is more difficult. Especially, since you already talked about this with a professional, and couldn't get it under control. Could it be that you have low self-esteem? Always wondering why anybody would date little old you?
I assume that you are not cheating on your bf and that the monogamy has been mutually agreed upon between the 2 of you. Are you permanently in temptation to cheat on him? Is he constantly making jokes about how he could fukc him, or him, or him?
What did he say about the open relationship he was in before you? Did he like that?

In the short term I would avoid anything that could be construed as controlling him or isolating him from others. Talk about your issues with him openly, if he cares about you, he will play along to make you more comfortable and keep his antenna up for when things get dicey.